_Meat poisoning_ may be avoided in the first place by exercising great care in regard to the odor of meat. Meat may hang to “ripen,” as the butchers say, but one must learn to distinguish between the odor of properly ripened meat, and that of even slightly tainted meat. Quite as important is the _rapid cooling_ of meat, poultry, fish, and soups that are not to be used at once. Cases of digestive disturbance and even actual poisoning sometimes occur when underdone meat, especially lamb, veal, or poultry, remains warm overnight. [Illustration: FIG. 64.——Composition of meats.] =The effect of heat upon meat.=——The _fat_ of meat is melted by heat. The meat fiber shrinks and hardens with intense heat; on the other hand it softens at a temperature somewhat below the boiling point of water. The structure of the muscle must be studied further in order to make the principles of cooking perfectly clear. If you think of the structure of the muscle cell as somewhat resembling the structure of an orange, you can picture quite clearly what happens under different conditions. Open a section of orange and separate some of the single cells. These may represent the muscle cells of meat that can be seen only under the microscope. If you cut across one of these tiny cells, the contents will escape, and this is what happens when the muscle cells are cut across. Then, too, if the muscle is heated, the juices will pass through the membrane of the cell, and this happens, too, if the meat is put into cold water. The substances in the juices of the meat which are not coagulated by heat are called the extractives, because they can be extracted by hot water. The most valuable protein matter remains behind in the muscle cell, however. Among these proteins are those known as meat albumin, and this behaves in cooking very much as does the white of egg,——that is to say, it coagulates. Bearing these facts in mind, we can decide just what to do in order to bring about the result that we desire in meat cookery, for sometimes we wish to extract the juices and sometimes we wish to have all, or nearly all, retained in the meat. We are now ready to state the principles of meat cookery as follows: 1. _Juices retained._ In broiling, pan broiling, roasting, and boiling the high temperature coagulates the meat albumin and hardens the fiber on the surface, thus forming a coating which prevents the further escape of juices. In the roasting and boiling of large pieces the temperature may then be lowered to prevent the further shrinking and hardening of the fiber in the interior of the meat, which comes from a protracted high temperature. With a very thick steak after the surface searing the cooking may be completed in the oven. 2. _Juices extracted._